Color Liquid Crystal Display Device and Image Display Thereof

ABSTRACT

There is disclosed a color liquid crystal display (LCD) device capable of displaying color images in response to direct entry of input data and/or instructions through operation of an associated coordinate pointing tool. Typically, this tool is a pen-like input device known as the “input pen” for use in determining the individual position for color display on the screen of a built-in LCD panel. A coordinate detector operates to recognize the position as designated by the input pen, generating and issuing an output signal indicative of the corresponding coordinate data. A color designator circuit designates a color as presently selected for color display. A memory device stores therein color data representative of the color designated. A memory controller is responsive to receipt of an address issued from the selected coordinate data for controlling the color data to be written into and read out of the memory. An output controller allows the color data read from the memory to be supplied to the LCD display screen as video data.

This application is a continuation of U.S. application Ser. No.08/725,642 filed Oct. 15, 1996. The disclosure of the above applicationis incorporated herein by reference as part of this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to liquid crystal display (LCD)devices, and more particularly to color LCD devices for use with atouch-sensitive pointing input device and an image display methodthereof.

2. Description of the Prior Art

Through the trend of complexity in computerization as to diversity ofinformation in the recent past, portable or “handheld” electronicinformation management tools including personal digital assistants(PDAs) have found increasing applications due to advantages such assmall size and light weight. In the thrust to achievement of suchadvanced handheld information management tools, the pen-input scheme isbecoming more important for permission of direct entry of input data orinstructions by use of a touch-sensitive coordinate pointing inputdevice known as a “pen” pointer in the art through an associatedtough-screen display panel in such a simple and easy way that allowsusers to “write down” by hand on a memo pad. As such pen-input scheme,several techniques have been proposed until today, including a techniqueof laminating a pen-input panel (tablet panel) on an associated displaypanel, a technique of common use of a display panel also as the tablet,and others.

One typical pen-input scheme incorporating the former technique has beendisclosed in, for example, Published Unexamined Japanese PatentApplication (PUJPA) No. 58-200384 and also in PUJPA No. 7-175591. Withthe prior art, an input tablet is constituted from two lighttransmissive substrates having lateral and longitudinal elongateelectrodes for position detection. The substrates may be made of glass,polycarbonate or other polymer material. When the pen pointer ismanually operated by users to draw a desired locus thereon whilerendering the pen pressed onto the surface of the tablet at a tip endthereof, a coordinate detector circuit operates to sense or detectcorresponding coordinates of a drawing position every time thecoordinates change. A control circuit is responsive to receipt of suchdetected coordinates for providing adequate image data indicative ofcharacter set or graphics as pursuant to the coordinate detectionresult, allowing a resultant drawing image to be visually indicated onthe LCD panel under the control of LCD driver circuitry.

Unfortunately, the prior art LCD devices suffer from the lack of abilityto process color images for display. A need has therefore been felt fora color-image displayable LCD device for use with the pen-pointer inputdevice permitting direct entry of input data and instructions.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a new andimproved LCD display scheme capable of avoiding the problem as facedwith the prior art.

It is another object of the invention to provide an improved color imagedisplayable LCD device while permitting direct entry of necessary dataor instructions by use of an associated touch-sensitive pointing inputdevice.

It is yet another object of the invention to provide an improved methodof displaying color images on LCD devices while permitting direct entryof input data or instructions using an associated touch-sensitivepointer.

To attain the foregoing objects, the present invention provides an LCDdevice having a display panel with an array of picture elements or“pixels” organized into a matrix, capable of displaying an image ashand-drawn by use of a touch-sensitive pointing input device, featuredin that the display device is arranged so that the image is displayablein more than one color thereon in response to operation of the pointinginput device.

In accordance with another aspect of the instant invention, there isprovided an LCD device including an LCD panel having an array of rowsand columns of pixels defining a matrix, a position commander fordetermining a certain position for color display on the display panel, acoordinate detector for recognition of the certain position asdetermined by the commander and for generating and issuing an outputsignal indicative of a corresponding coordinate data, a color designatorfor designation of the kind of a color being selected for such colordisplay, a memory device for storage of color data representative of thecolor as presently designated, a memory controller responsive to receiptof an address generated from the selected coordinate data forcontrolling the color data to be written into and read from the memory,and an output controller for allowing the color data read from thememory to be output onto the display panel as image data.

In accordance with still another aspect of the invention, the commanderincludes a pen-shaped touch-sensitive input device for use in drawingany desired locus being subject to color display on the display panel,while the coordinate detector includes a recognition function module forrecognizing the locus drawn by the pen pointer thereby to provide anoutput being issued as X- and Y-coordinate data corresponding to thepixel dots on the display panel.

In accordance with a further aspect of the invention, the recognitionfunction module may include a pressure sensor, an electrostatic sensoror a heat sensor.

In accordance with a yet further aspect of the invention, the colordesignator is comprised of a color designation area as provided inadvance for a respective one of colors on the display panel permittingselection of any desired color in response to the commander. With theinvention also, the color designator may be a color selection menuallowing the operation mode to be set in a color selection mode andpermitting selection of a desired color through the color selectionmode. The display panel may be of the active matrix type havingthin-film transistors (TFTs) disposed at the pixels thereon.

In accordance with a still further aspect of the invention, there isprovided a method for displaying a color image on an LCD panel with amatrix of rows and columns of pixels by using a pen-like touch-sensitiveinput device operatively associated therewith, which method includes thesteps of designating a color to be displayed in advance, drawing on thedisplay panel a locus being color-displayed by use of the pen pointerinput device, providing the address of an associated data storage devicebased on the resulting coordinate data corresponding to the locus drawn,writing the selected color data into the storage device at thedesignated address thereof, and reading color data from the storagedevice thereby generating and issuing the same to the display panel asimage data.

In accordance with the invention, the LCD panel has a matrix of rows andcolumns of pixels. To display a color image, a color designation meansacts first to designate or determine the color to be displayed. Thiscolor designation may be performed by execution of pointing one of colordesignation areas each predefined for the individual color on a displaypanel; or alternatively, the same may be attained by setting theoperation mode in a color selection mode through operation of a colorselection menu.

Then, a position commander unit operates to instruct a specific positionbeing subject to such color display on the display panel. Morepractically, the commander may be a touch-sensitive pointing inputdevice, which is generally known as a “pen pointer” tool This penpointer is for use in drawing any desired line of locus to becolor-displayed on the LCD panel screen. Each position designated by thecommander is next recognized by a coordinate detector unit, whichgenerates and issues corresponding coordinate data at an output thereof.The coordinate detector includes a recognizer for recognition of thelocus as drawn or defined by movement of the pen pointer in such a waythat the detector issues an output of recognizer as data indicative ofX- and Y-coordinates corresponding to pixels or dots on the displaypanel. The recognizer here may be a pressure sensor, electrostaticsensor, heat sensor, or the like.

A storage controller unit is responsive to receipt of the resultingcoordinate data for generating and issuing an address selected. Based onthe address, the controller also serves to control read/write operationsof color data with respect to a memory associated. The color data storedin the memory is then read out under the control of the storagecontroller to be supplied as video data to the display panel. In thisway, it becomes possible to display a color image by use of pen inputdevice.

These and other objects, features and advantages of the invention willbe apparent from the following more particular description of onepreferred embodiment of the invention, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an overall configuration of a colorLCD device in accordance with one embodiment of the invention.

FIG. 2 is a diagrammatical representation for explanation of a colordata storage scheme as employed in the LCD device of FIG. 1.

FIGS. 3(a) to 3(c) depict some models of the contents of a memory in theLCD device shown in FIG. 1.

FIG. 4 illustrates a configuration of table data as stored in a colordesignator circuit of the embodiment of FIG. 1.

FIG. 5 shows a configuration of electrical circuitry of an LCD panel asemployed in the FIG. 1 embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a liquid crystal display (LCD) device in accordancewith one preferred embodiment of the invention includes an LCD panelwith a matrix of rows and columns of picture elements or “pixels,” whichmay also be called the “dots” in some cases. The LCD panel comes with acoordinate detector device 2 for detection of coordinates as input by anassociated pen-shaped touch-sensitive pointing input device known as an“input pen” or “pen pointer” in the art. Here, the LCD panel is of theactive-matrix type which may be configured as shown in FIG. 5. As shown,the active-matrix LCD panel incorporates a matrix of pixels, each ofwhich is at a corresponding one of cross points or intersections betweenhorizontal scanning lines 52 and vertical signal transmission lines 53.The individual pixel includes therein a switch element 50, whichselectively turns on and off controlling adequate transfer of imageinformation to an associative display medium. This medium may be aliquid crystal material 51. The switch element may be a three-terminalelement, typically a thin-film transistor (TFT) having the gate, sourceand drain electrodes. The scan lines 52 are connected to the gates ofTFTs 50, whereas the signal lines 53 are to the sources (or drains)thereof.

As shown in FIG. 1, the coordinate detector 2 includes a pair ofX/Y-coordinate recognition sensors 21 for recognition of the position ofan arbitrary point as presently designated by the input pen 1, bydetecting the X- and Y-coordinates thereof on the LCD display panel. Thedetector 2 also includes a coordinate detector circuit 22, which isresponsive to receipt of the recognition data as derived from theX/Y-position recognition sensors 21 for generating and issuing at theoutputs X- and Y-coordinate data that correspond to dots on a one-to-onecorrespondence basis. The sensors 21 may be pressure sensors,electrostatic sensors, heat sensors, or the like.

The coordinate detector 22 is connected to a memory controller circuit3. This controller is to perform physical address settings andread/write control for an associative memory device 4 (described later).More specifically, the controller 3 generates and issues a physicaladdress(es) for data write in memory 4 in response to the coordinatedata (X- and Y-coordinate data) as detected by coordinate detector 22.Controller 3 also receives information sent from a sequence controllercircuit 5 (later described) to generate when data write a write commandsignal such as write enable (WE) at a certain timing. During read mode,controller 3 attempts to control data read operation at memory 4 byproviding physical address control for display on the LCD panel andgenerating a necessary signal (control signal) therefor.

The memory controller 3 is connected to the memory 4 and also to a colordesignator circuit 6 and a panel display timing signal generator circuit7. The coordinate detector 2, memory controller 3, color designator 6and timing generator 7 are connected to the sequence controller circuit5 so that they operate under the control of it. Memory 4 is connectedthrough an RGB conversion table 8 to an output controller circuit 9. Thepanel display timing generator 7 is also connected to output controller9.

The memory 4 has in its memory space a prescribed number of addresses asequivalent in number to the resolution of the display panel, namely,equal to the total number of pixel dots thereon. Memory 4 can storetherein N-bit data enabling handling of 2^(N) colors of image data. Byway of example, in cases where sixteen (16) different colors arerequired for display, the memory is designed to be 4-bit data storablememory. Further, memory 4 has N sets of storage regions; for example, inthe case of 16 different colors, it is designed to have four sets ofstorage regions MEM0, MEM1, MEM2, MEM3 as shown in FIG. 2, each of whichcan store therein 4-bit data separately. Note here that FIG. 2diagrammatically represents a model of the operational correlation ofcoordinate detector 2 and memory 4.

The color designator 6 operates when predefined color selection(designation) coordinates are pointed on the LCD display panel to set acertain color data corresponding to the presently pointed color thereon.Here, the “color designation coordinates” may refer to an area asprovided on the LCD display panel for the individual color. Forinstance, in cases where sixteen (16) colors are needed for display, 16separate areas are provided on the panel, each of which is associatedwith a corresponding one of such colors required. With such anarrangement, selecting any desired color becomes available by execution,using pen 1, of “pointing” color designation coordinates (colordistinction area) as desired for color display.

It should be noted here that the color data may be specific datavariable in value from zero (0) to 2^(N−1) that can be handled orprocessed by memory 4 with N sets of storage regions. For example, inthe situations where 16 different colors are to be implemented for use,the data is designed to have any value as selected from “0” to “15” thatcan be handled by memory 4 with four sets of storage regions MEM0-MEM3.The color designator 6 has one exemplary built-in table as shown in FIG.4. This table shown is for use in 16-color display schemes; for example,when a “black” is selected based on the color selection coordinates, acorresponding digital color data “1111” is set. Alternatively, when a“red” is designated due to color designation coordinates, a color data“0001” will be set. In such cases, allocation between colors and colordata items may be determined in an arbitrary manner.

In the illustrative embodiment the color selection coordinates (colordistinction area) are arranged on the LCD display panel enablingselection of any desired color for display by use of the “pen-pointing”techniques; this may alternatively be modified such that an exclusivecolor selection menu is provided at a selected position on the displayscreen allowing users to operate it to attain selection of any color fordisplay. In other words, operating the color selection menu causes thescreen to change in operation mode so that it is set in a colorselection mode for permission of color selection by way of suchresultant color selection screen. This may advantageously avoid the needof providing in advance the color distinction areas on the LCD displaypanel enabling more efficient use of display screen in area.

The panel display timing generator 7 functions to generate and issue atits output a write synchronization (sync) signal, an operation clocksignal, a reset command signal (an initializing signal) and others forthe LCD display panel, memory controller 3, and output controller 9. TheRGB conversion table 8 is for conversion of data read from the memory 4into corresponding actual color data during display operation of the LCDpanel. Output controller 9 operates to provide retiming,digital-to-analog (D/A) conversion and level-shift operations of videodata and display control signals.

In the embodiment thus arranged, a color selected by use of either thecolor selection coordinates (color distinction area) or the colorselection menu on the LCD panel screen is converted by the colordesignator 6 to a corresponding color data, which is then stored inrespective storage regions of the memory 4. By way of example, assumethat sixteen (16) different colors are available for display: in thiscase, resultant color as selected through operation of the colorselection coordinates (color distinction area) or the color selectionmenu is converted using the table (see FIG. 4) of color designator 6into 4-bit color data, and is then stored in a respective one of thestorage regions MEM0-MEM3 of memory 4 shown in FIG. 2.

The color data stored in the memory 4 in this way is thereafter read outof it under the control of memory controller 3 to be sent forth to theRGB conversion table 8. RGB conversion table 8 is rendered operative toconvert the input color data to RGB data for actual display on the LCDpanel screen, which is then passed to the output controller 9. Outputcontroller 9 attempts based on a signal(s) from the panel display timinggenerator 7 to display such RGB data on the LCD panel as videoinformation. In this way, any desired color display is available inresponding to input by pen 1.

The operation of the illustrative embodiment will be described in detailas follows.

The following description assumes that sixteen (16) different colors areemployed for display. Imagine that as shown in FIG. 2, a curvature lineA is to be displayed in “black” whereas a straight line B is in “red” onthe LCD screen. Consider here that the display screen is initiallydisplayed in “white” as its background color.

Under the above condition, the memory 4 has four sets of separatestorage regions MEM0-MEM3 as shown in FIG. 2, while the content of colordata being stored in each region is shown in FIGS. 3A to 3C. FIG. 3Ashows the initial condition of such storage regions MEM0-MEM3, all ofwhich store therein logic data “0” since the LCD background color is“while” as mentioned previously. FIG. 3B illustrates the storagecontents of respective regions MEM0-MEM3 as observed just aftercompletion of pen-input of the curve A of FIG. 2, whereas FIG. 3Cdepicts the contents of regions MEM after pen-input of the straight lineB of FIG. 2.

First, the operator designates in advance his or her desired color to bedisplayed on the LCD screen. This color designation is attained eitherby execution of “pointing” the color designation coordinates (colordistinction area) or by using a color selection menu as displayed on thescreen.

Since this example assumes that the curve A is first displayed in“black,” the operator selects the “black” by pointing the colordesignation coordinates or by making use of the color selection menu.The resulting color selected is then converted by the color designator 6into color data. Practically, such designated color is converted usingthe conversion table (see FIG. 4) and is sent forth as output data. Inthis case, the “black” is converted into a 4-bit digital signal “1111.”

After completion of the color designation for display in the foregoingway, the operator then uses the input pen 1 to draw his or her desiredlocus on the LCD display panel. In this example the curve A ishand-drawn on the display panel. The resulting locus as drawn on thedisplay panel is output by the coordinate detector 2 as appropriatecoordinate data (the data representative of X- and Y-coordinates), andthereafter is input to the memory controller 3. In responding to this,memory controller 3 generates and issues at its output physicaladdresses based on the input coordinate data, attempting to sequentiallywrite color data into memory 4 at such addresses generated. The entirestorage space of memory 4 is divided into four regions MEM0-MEM3allowing the 4-bit color data to be written into these regions MEM. Theresult of such data write into regions MEM is demonstrated in FIG. 3B.

Then, for display of the straight line B in “red” on the LCD panel, theoperator selects the “red” through pointing of the color designationcoordinates (color distinction area) or using the color selection menu.Any resultant color selected is then converted by the color designator6. In this case the selected color is converted by the conversion table(see FIG. 4) into 4-bit color data

After completion of the color designation for display, the operatorattempts to hand-draw using the input pen 1 his or her desired locus,namely, line B of FIG. 2 for example on the LCD display panel. The locusdrawn is output by the coordinate detector 2 as X/Y-coordinate data andis then supplied to the memory controller 3, which generates and issuesat its output physical addresses sequentially writing color data intomemory 4 at such addresses generated. Practically, the 4-bit color data“0001” is stored in four regions MEM0-MEM3 of FIG. 2, respectively. Theresult of such data storage in regions MEM is presented in FIG. 3C.

The resultant color data bits as stored in the memory 4 are later readsequentially from it under the control of memory controller 3 to besupplied in this order to the RGB conversion table 8. RGB conversiontable 8 automatically converts the input color data to corresponding RGBdata, which is then fed to the output controller 9. Output controller 9executes D/A conversion for the RGB data as input thereto deriving atits output an analog color video signal, which is then supplied to theLCD panel. In this way, the pen-input locus patterns (curve A andstraight line B) are finally displayed on the LCD screen in theoperator's designated colors, e.g., “red” or “black” in this case.

It will possibly be desired that the locus patterns are in other colors.If this is the case, the aforesaid operation will be repeated while theoperator occasionally selects his or her preferred color(s) by executionof pointing the color designation coordinates (color distinction area)or using the color selection menu available at every step for colorselection.

As necessary, an extra selection menu for selection of the backgroundcolor and line colors may be additionally arranged on the display panel.To attain such background-color designation, it should be required thata presently designated color data be written into the memory 4 atcorresponding addresses thereof. This may be accomplished by employing aspecific scheme as follows: reading data out of memory 4, and replacingthe “old” data being previously stored at an address of the backgroundcolor data before such background color designation with the updatedbackground color data as presently selected. This data replace schememay be attained using either one of an exclusive hardware arrangementand software programs.

In addition, while the illustrative embodiment has been described underthe assumption that it is applied to the case of 16-color images basedon 4-bit data, this invention is not exclusively limited thereto, andmay be modified in arrangement to be applicable for any other casesrequiring an increased number of colors for display. Furthermore, thepen-input technique as employed in the embodiment may be replaced withany other functionally equivalents, including the use of a multi-layeredpanel structure with the pen-input panel being stacked on the displaypanel, the use of a common panel structure allowing a panel to functionboth as the display screen and as the pen-input sheet.

It has been described that the present invention can provide the LCDdisplay device permitting pen input on its display panel and the displaymethod therefor.

1. A display device for displaying a color image comprising: a displaypanel comprising a plurality of pixels located in a matrix, where eachof the plurality of pixels has a switching element; a pointing devicefor pointing to identify a first portion in a color selecting portion onthe display panel so as to select a color and for pointing to identify asecond portion on the display panel after selecting the color on thedisplay panel so as to select a locus for the selected color; acoordinate detector for outputting a first data derived fromX-coordinate data and Y-coordinate data corresponding to the identifiedfirst portion and second data derived from X-coordinate data andY-coordinate data corresponding to the identified second portion; acolor designator for setting, using the first data, color datacorresponding to the selected color; a memory device including storageregions for storing the color data; a memory controller for generatingan address corresponding to the second data, the address identifying thesecond portion on the display panel where the color is to be output; andan output controller for outputting video data to the display panel,wherein the video data is generated by using the color data and theaddress.